Over the course of their research the scientists found that they could guess a user's pin 90 per cent of the time - if the thermal image was taken within 15 seconds of a pin being tapped in.

For Android users who use finger-drawn patterns, the scientists could guess the right shape 100 per cent of the time.

"Even if a thermal image was snapped 30 seconds after a user drew it onto their phone screen.

"The increasing amount of sensitive data available on personal mobile devices, such as personal photos, call logs, bank accounts, and emails underlines the need to secure them against various kinds of malicious attacks," scientists said in a research paper.

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